|
Stoichiometry is the culmination of
many concepts in chemistry. It integrates dimensional
analysis, moles and molar mass, molar volumes of gases,
concentrations and balanced chemical equations to use
information about one species in a reaction to determine
information about another species in the same reaction.
Review
Chemical equations are used to relate reactants and products in a
chemical reaction. Dimensional analysis is a technique that uses
ratios of equivalents to convert units. The KUDOS method is a
method for solving word problems. Molarity is a concentration unit
showing the ratio of moles of solute to volume of solution.
Mole-Mole problems
The balanced equation gives the ratio of moles of each species in
the reaction. The balanced equation is used to determine mole
ratios for use in dimensional analysis when converting from the
moles of one species to the moles of another. Moles is the only
unit that may be used to convert from one chemical to another�mass
or volume cannot be used to convert between chemicals, just within
the same one.
Mole-Mass & Mass-Mass problems
Molar mass is an equivalent between the mass in grams and moles of a
substance. The molar mass is used to convert between moles of a
substance and mass in a stoichiometry problem.
Mole-Volume problems for solutions
The concentration, in molarity, of a solution gives the equivalent
for moles of the solute and liters of solution. The molarity can be
used to convert between moles and volume of a solution in
stoichiometry problems.
Mole-Volume problems for gases
The volume of 1 mole of any gas at standard temperature and pressure
is 22.4 L. The molar volume of a gas can be used to convert between
moles and volume of a gas at STP in stoichiometry problems. If a
problem asks for the volume at non-standard temperature or pressure,
find the STP volume using stoichiometry and then use the appropriate
gas law to convert to the desired temperature or pressure.
|
